EAB VE12 Tube Preamp Dual Power Supply Question????

[DerEber]

Thanks for the update.

The original unit went to unbalanced resistor summing-network. From there to L or/and R Sum Channels. (Was it VS21?)
It was not super optimal noise wise, but they saved the extra transformer.
I once did a 2 to 1 Test-box.
My resistor network was not original, but following the summing gain and all other informations on the schematics there were only few interpretations left.

 

[leadbreath]

Yes interesting, my client has quiet a few of these units, I sid see some photos he provided, think one was master channel and other ine had LOADS of transformers/no controls??

 

[leadbreath]

Apparently the master channel is based on the V41 pre(the one with Ef12 octals) but not sure....

 

[leadbreath]

The one we worked on had some type of inductor just before output stsge, my business partner ( who is waaayyy more technical than me) said it reminder him of V72??? But once again cant confirm...

 

[leadbreath]

He took some phots of unit ee had, will get them posted here....

 

[leadbreath]

Pity there isnt more info on there units thet seem quality, and as agreed the noise floor it bit high but definitley is a very nice sounding pre with loads of "colour".
Wish they were mine....

 

[leadbreath]

Think changing the tubes will help with noise but e283cc are not cheap!!

 

[ivan]

VS-21 summing amp

 

[ivan]

Here is my VE12 schematic.
I racked some channels long time ago. Heater voltage was DC 12.6V. Heaters on VE12 are connected in series.
I put a simple SRPP on the output but I don't remember which tube. It was a long time ago.

 

[leadbreath]

Nice one Ivan!!

 

[ivan]

I put also both schematics in Technical Documents on the forum.
https://groupdiy.com/threads/eab-geiling.83824/

 

[leadbreath]

Thanks Ivan, let us know if you got any more EAB schematics, we might be doing some more units that client is providing...

 

[ivan]

Unfortunately I only have these two schematics.
This is how it looked racked because unfortunately on the VE12 the faders were defective and the front panels were scratched.
One of the mod was placing the instrument input jack between the input transformer and the tube grid, and the other was an additional position on the HP switch where the two primaries of the input transformer are directly connected without two 1uF capacitors and with that there is no HP filter.

If you add 48V, please make some protection because those input transformers are wound with thin wire and are very sensitive.

 

[leadbreath]

WOW beautiful work there man, very nice!!!

 

[leadbreath]

Yeah seems like we lucked out on our one the input tx was fine fader was ok, all we really did was recap and power the fucker up with faceshield on!!

 

[leadbreath]

And yes did recommend cliwnt to not use phantom on unit as input tx wiring was very brittle, he said he only used tube mics so all good!!

 

[braca_mustang_1964]

Hi there,
I am using EAB V12c almost 12 years. Input stage of this channel is pure original VE 12 of EAB, with tubes E283CC, input transformer (I think it is telefunken), and passive eq with two tubes. There is attenuation with 20, 40 and 60dB. Law pass filter in 40 and 120hz.
This Input EAB modul does not have balance out, so my tehnician put out modul from Studer C 37 with original tranformer and two tubes E188CC, we wanted as clean as possible balance out, but still flavor. I have also original EAB out modul but we wonted to try this option and I am sure that we did not make a mistake.
I made a lot of test with other pre amps (API 512c , MCI 500, Neve 1073) but I like sound of this EAB channel, warm and rich, for me huge sound on vocal and accustic guitar.
In meantime I got another 11 module, and I have plan to recreate tube mixer 12 channel. My question is someone give mi advice:
1.Is ECC83 possible good enough for replacing E183CC
2.How to make direct out from each module ( with trannye or with IC transfomless
3. I am musician with small electronic knowledge, what suggest for buss bar
Any schematics on this topic

Best regards

 

[gyraf]

Looks like there is quite low output drive capability on these units, both level and impedance. Perhaps try with the simple amplifier stage from the G-Pultec, that one may be suitable..

edit: The G-Pultec stage will run on the voltages you already have - 6.3V/350mA for the heater and 200V ca. 5-10mA for the anode

/Jakob E.

 

[leadbreath]

Hi, thanks for posting this info, do you have sny schematics?? I see you mention a "C" version? Do you know of/ have any other types of these? I ask because the one I worked on was different to schematic...

 

[leadbreath]

As for your questions:
1) E283CC is hi spec ECc83 but tube pin outs are different. So without modding unit its not possible.
2) As mentioned here before looks like stock VE12 as per schemo is is meant to be incorporated with mixbuss of console, so needs exrta output stage, can recommend Gyrafs as mentioned got a few of hid G-Pultecs and love them!!